The Federal Aviation Administration has developed required navigation performance (RNP) protocols to facilitate the management of air traffic. Under these protocols, RNP values (e.g., 0.1 to 30 nautical miles) may be assigned to various particular segments, or legs, of an aircraft's flight plan. For example, when an aircraft approaches an airfield, the aircraft may be assigned a particular flight plan segment, or landing leg, by the air traffic controller. Depending upon air traffic, the air traffic controller may also communicate to the aircraft's crew (e.g., pilot) an RNP value associated with the landing leg (e.g., 2.0 nautical miles). The RNP value defines an airspace within which the aircraft should remain for a predetermined percentage (e.g., 95 percent) of the total flying time. This airspace may be referred to as the RNP Obstacle Evaluation Area or, more simply, the RNP corridor. If the aircraft is RNP capable and if the pilot is appropriately certified, the pilot may attempt to travel the assigned landing leg while remaining within the RNP corridor. If, during the landing attempt, the aircraft breaches an RNP boundary and the leaves the corridor, a warning indicator (e.g., a hazard light) is produced inside the aircraft's cabin and the landing may be aborted and attempted again at a later time.
Many conventional aircraft display systems do not provide a visual indication of the location of the RNP corridor boundaries relative to the aircraft's position and projected flight path. Such conventional aircraft display systems do not graphically indicate whether, under the current flight parameters (e.g., aircraft speed, bank angle, pitch, yaw, wind sheer, etc.), the aircraft will travel outside of the RNP corridor. Consequently, the flight crew may need to interpret data from various aircraft systems to estimate the location of the RNP corridor boundaries. This can increase the flight crew's overall workload. In addition, this may deter the pilot from taking corrective actions to maintain the aircraft within the RNP corridor. As a result, the likelihood of an RNP corridor containment breach and, thus, an aborted landing, is increased.
It is thus desirable to provide an aircraft display system and method for graphically indicating the boundaries of an RNP corridor on a display (e.g., a navigational map display) in an intuitive manner. In addition, it would be desirable for the RNP corridor to be scalable to the field of view of the map display to thereby permit the pilot (or other crew member) to view the aircraft flight plan and projected flight path relative to the RNP corridor in a desired level of detail. Finally, it would be desirable if the aircraft display system were configured to generate an alert if the aircraft is currently outside of the RNP corridor or is projected to breach an RNP corridor boundary. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.